Designation D6438 − 05 (Reapproved 2015) Standard Test Method for Acetone, Methyl Acetate, and Parachlorobenzotrifluoride Content of Paints, and Coatings by Solid Phase Microextraction Gas Chromatogra[.]
Trang 1Designation: D6438−05 (Reapproved 2015)
Standard Test Method for
Acetone, Methyl Acetate, and Parachlorobenzotrifluoride
Content of Paints, and Coatings by Solid Phase
This standard is issued under the fixed designation D6438; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision A number in parentheses indicates the year of last reapproval A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
1 Scope
1.1 This test method is for the determination of acetone,
methyl acetate, or parachlorobenzotrifluoride (PCBTF), or
combination of any of the three, in paints and coatings, by solid
phase microextraction (SPME) headspace sampling, and
sub-sequent injection into a gas chromatograph It has been
evaluated for cellulose nitrate, acrylic, and urethane
solvent-borne systems The established working range of this test
method is: acetone, 28 to 90 %; methyl acetate, 12 to 22 %;
parachlorobenzotrifluoride, 10 to 17 % There is no reason to
believe that it will not work outside these ranges A minor
modification of this test method would make it suitable for the
analysis of the same analytes in water-borne coatings (seeNote
1)
N OTE 1—Water-borne paints are internally standardized and diluted
with water followed by addition of solid sodium chloride.
1.2 The values stated in SI units are to be regarded as
standard No other units of measurement are included in this
standard
1.3 This standard does not purport to address all of the
safety concerns, if any, associated with its use It is the
responsibility of the user of this standard to establish
appro-priate safety and health practices and determine the
applica-bility of regulatory limitations prior to use.
2 Referenced Documents
2.1 ASTM Standards:2
D3925Practice for Sampling Liquid Paints and Related
Pigmented Coatings
D6133Test Method for Acetone, p-Chlorobenzotrifluoride,
Methyl Acetate or t-Butyl Acetate Content of
Solvent-borne and WaterSolvent-borne Paints, Coatings, Resins, and Raw Materials by Direct Injection Into a Gas Chromatograph
E180Practice for Determining the Precision of ASTM Methods for Analysis and Testing of Industrial and Spe-cialty Chemicals(Withdrawn 2009)3
3 Terminology
3.1 Abbreviations:
3.1.1 PCBTF—parachlorobenzotrifluoride
(4-chlorobenzotrifluoride)
3.1.2 MCBTF—metachlorobenzotrifluoride
(3-chlorobenzotrifluoride)
3.1.3 SPME—solid phase microextraction 3.1.4 VOC—volatile organic compound 3.1.5 PEG/DVB—polyethylene glycol/divinylbenzene 3.1.6 FID—flame ionization detector
3.1.7 MS—mass selective or mass spectral 3.1.8 SIM—selected ion monitoring 3.1.9 GC—gas chromatograph 3.1.10 Sr—repeatability standard deviations 3.1.11 SR—reproducibility standard deviations 3.1.12 r—repeatability, 95 % confidence limit 3.1.13 R—reproducibility, 95 % confidence limit
4 Summary of Test Method
4.1 A suitable aliquot of whole solvent-borne paint is internally standardized and diluted with dioctyl phthalate The headspace of this solution is sampled with an SPME fiber, which is then thermally desorbed in the injection port of a gas chromatograph onto a suitable capillary column Either a flame ionization or mass specific detector may be used to measure peak areas of analytes and internal standards
1 This test method is under the jurisdiction of ASTM Committee D01 on Paint
and Related Coatings, Materials, and Applications and is the direct responsibility of
Subcommittee D01.21 on Chemical Analysis of Paints and Paint Materials.
Current edition approved June 1, 2015 Published June 2015 Originally
approved in 1999 Last previous edition approved in 2010 as D6438 – 05 (2010).
DOI: 10.1520/D6438-05R15.
2 For referenced ASTM standards, visit the ASTM website, www.astm.org, or
contact ASTM Customer Service at service@astm.org For Annual Book of ASTM
Standards volume information, refer to the standard’s Document Summary page on
the ASTM website.
3 The last approved version of this historical standard is referenced on www.astm.org.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959 United States
Trang 25 Significance and Use
5.1 In order to calculate the volatile organic content (VOC)
of paints containing EPA exempt solvents, it is necessary to
know the acetone, methyl acetate, or
parachlorobenzotrifluo-ride content This gas chromatographic test method provides a
simple and direct way for measuring these solvents Each
analyte is measured with respect to a unique internal standard
For acetone, the internal standard used is acetone-d6, for
methyl acetate it is methyl acetate-d3, and for PCBTF it is
metachlorobenzotrifluoride (MCBTF) These unique analyte/
internal standard pairs behave very nearly as single solvents
with respect to evaporation rate and adsorption rate onto a
coated silica fiber (SPME) but are separable on a gas
chro-matograph (GC) capillary column The only critical analytical
technique required for successfully performing this test method
is the ability of an analyst to weigh a paint sample and internal
standard, corresponding to the analyte of interest, into a septum
capped vial After weighing, solvent evaporation has no effect
on the final value of the determination Since whole paint is not
injected into the gas chromatograph, the analytical system is
never compromised
6 Apparatus
6.1 Manual SPME Holder,4fitted with partially crosslinked
polyethylene glycol/divinylbenzene (PEG/DVB) fiber
assembly, 65–µm film thickness
6.2 Gas Chromatograph, FID Detection—Any capillary gas
chromatograph equipped with a flame ionization detector may
be used Temperature programming capability is desirable, but
isothermal operations may be utilized
6.2.1 For FID instrument conditions, seeTable 1
6.2.2 Inlet Liner, 0.75-mm should be placed in the injection
port.4
6.2.3 Integrator—Any electronic integrator that can
accu-rately quantify a gas chromatographic peak area is acceptable
6.3 Gas Chromatograph, Mass Selective (MS) Detection—
Any capillary gas chromatograph equipped with a mass selec-tive detector may be used The detector must be capable of measuring in the selected ion monitoring (SIM) mode at dwell times of 100 milliseconds or less
6.3.1 For MS instrument conditions, seeTable 2
6.3.2 Inlet liner, 0.75-mm, should be placed in the injection
port.4 6.3.3 The instrument should have a software data system to allow extraction and integration of the SIM ions
7 Column and Fiber Conditioning
7.1 Either or both capillary columns should be conditioned according to the manufacturer’s recommendation The col-umns may then be used indefinitely without further condition-ing
7.2 The SPME fiber should be conditioned and used accord-ing to the manufacturer’s recommendation
7.3 The SPME fiber should be inserted into a 260°C injection port for 30 s prior to daily use
8 Reagents and Materials
8.1 Purity of Reagents—Reagent grade chemicals shall be
used in all tests Unless otherwise indicated, it is intended that all reagents shall conform to the specifications of the Commit-tee on Analytical Reagents of the American Chemical Society, where such specifications are available.5Other grades may be used, provided it is first ascertained that the reagent is of sufficiently high purity to permit its use without lessening the accuracy of the determination
8.2 Carrier Gas, Helium of 99.995 % or higher purity 8.3 Acetone -d6 , 99.9 % isotopic purity.
4 The sole source of supply of the manual holder and fibers known to the
committee at this time is Supelco Company, Supelco Park, Bellefonte, PA
16823-0048 If you are aware of alternative suppliers, please provide this
informa-tion to ASTM Internainforma-tional Headquarters Your comments will receive careful
consideration at a meeting of the responsible technical committee, 1
which you may attend.
5Reagent Chemicals, American Chemical Society Specifications, American
Chemical Society, Washington, DC For suggestions on the testing of reagents not
listed by the American Chemical Society, see Analar Standards for Laboratory Chemicals, BDH Ltd., Poole, Dorset, U.K., and the United States Pharmacopia and National Formulary, U.S Pharmacopeial Convention, Inc (USPC), Rockville, MD.
TABLE 1 FID Instrument Conditions
Detector: Flame ionization
Column: 60 m × 0.25 mm 100 % polyethylene glycol, 0.5-µm
film thickness
Flow Rage: 1.0 mL per minute (20 cm per second)
Split Ratio: 200 to 1
Fiber desorption time: 5 to 6 sA
Temperature, ° C
Rate 1 30° per minute to 100°, hold 10 min
Rate 2 30° per minute to 240°, hold 2 min
AIf the fiber desorption is carried out longer than 5 or 6 s, the acetone peaks
exhibit tailing A 5 to 6–s desorption time transfers 98 to 99 % of the analytes to the
capillary column The fiber may be cleaned by inserting it into the GC inlet for 15
s after analytes of interest have eluted.
TABLE 2 MS Instrument Conditions
Detector: Electron ionization or mass selective Detection Mode: Selected ion monitoring (SIM) of ions m/e 58, 64,
74, 77, and 180 Dwell Time: 100 milliseconds or less Solvent Delay: 0.0 min
Column: 25 m × 0.20 mm 5 % phenyl/95 % methyl
polydimethylsiloxane
Flow Rate: 1.0 mL per minute (20 cm per second)
Fiber desorption time: 5 to 6 sA
Temperatures, ° C
Rate 1 10° per minute to 90°, hold 1 min Rate 2 40° per minute to 240°, hold 1 min
AIf the fiber desorption is carried out longer than 5 or 6 s, the acetone peaks exhibit tailing A 5 to 6–s desorption time transfers 98 to 99 % of the analytes to the capillary column The fiber may be cleaned by inserting it into the GC inlet for 15
s after analytes of interest have eluted.
Trang 38.4 Methyl Acetate -d3, 99.9 % isotopic purity (seeNote 2).
8.5 Parachlorobenzotrifluoride, technical grade, 99+ % (see
Note 3)
8.6 Metachlorobenzotrifluoride, 97 %, (seeNote 4)
8.7 Dedicated Syringes, 250-µL syringes, and Disposal
Syringes, 1.0 mL.
8.8 Septum Vials, 22 or 40 mL, with fluorocarbon-faced
silicone septa
N OTE 2—Methyl acetate-d3 was prepared by the acid-catalyzed
reac-tion of methanol with acetic-d3 acid, 99.9 % isotopic purity.
N OTE 3—Parachlorobenzotrifluoride contained 0.5 % of the meta
iso-mer and 0.1 % of the ortho isoiso-mer.
N OTE 4—The metachlorobenzotrifluoride standard was
chromato-graphically analyzed on a 60–meter 100 % polyethylene glycol column
(see 6.2 ) and exhibited only a single peak.
9 Preparation of Apparatus
9.1 Place 6-mL dioctyl phthalate into a 22 or 40-mL vial and
seal with a septum cap
9.2 Using dedicated 250-µL syringes, weigh approximately
100 mg each of parachlorobenzotrifluoride and
metachloroben-zotrifluoride to 0.1mg into the vial Excess solvent should be
wiped from the syringe needle prior to piercing the septum
Any solvent adhering to the outside of the septum cap after
making the transfer should be wiped off with tissue Weigh the
amounts of PCBTF and MCBTF to 0.1 mg Repeat the
procedure by adding approximately 150 mg each of acetone,
acetone-d6, methyl acetate, and methyl acetate-d3, and weigh
each component to 0.1 mg
9.3 Manually shake the vial for 15 s to mix the contents and
then let the vial stand at room temperature for 30 min
9.4 Remove the cap and wipe the septum to remove solvent
from the inner surface and reseal immediately, or replace the
septum with a new one
9.5 Sample the headspace with the SPME fiber for 60 s
9.6 Desorb the SPME fiber for 5 to 6 s in the injection port
of the gas chromatograph using either the conditions described
in6.2or6.3
9.7 Clean the fiber by placing it in the GC injection port for
15 s after the analytes of interest have passed through the
capillary column
9.8 If using the GC/FID procedure measure the peak areas
of the three analytes and three standards by integration (See
Note 5) Curve fitting software for measuring peak areas is
advantageous in some instances
N OTE 5—The approximate retention times in minutes are as follows:
acetone-d6, 10.35; acetone, 10.56; methyl acetate-d3, 11.06; methyl
acetate, 11.22: MCBTF, 22.33; PCBTF, 23.53.
9.9 If using the GC/MS procedure, measure the peak areas
for the extracted ions indicated inTable 3
9.10 Calculate response factors (RF) for acetone, methyl
acetate, and PCBTF according to the equation given in 10.4
The numerical values should agree within 1 % of each other
10 Procedure
10.1 Using a disposable 1-mL syringe, weigh 0.5 to 1.0 g of well mixed paint (see Note 6 and Practice D3925) into a septum-capped vial containing 6 mL of dioctyl phthalate The paint should drop directly into the dioctyl phthalate Carry out the same procedures as described in 9.3 – 9.7
N OTE 6—Since acetone and methyl acetate are extremely volatile, it is advisable to split the initial paint sample to be tested into two or more samples in suitable secondary containers.
10.2 Determine which, if any, of the three exempt solvents are present in the paint sample and if interfering peaks are present at the retention times corresponding to the retention times of the internal standards (see Note 7)
N OTE 7—The area of an interfering peak, if any, found in 10.2 , may be subtracted from the area of the standard peak when carrying out 10.5
10.3 Into a septum-capped vial containing 6 mL dioctyl phthalate, weigh 0.5 to 1.0 g of paint sample to 0.1 mg Add
100 mg of each of the internal standards, corresponding to the analytes found in 10.1 Carry out the same procedure as described in9.3 – 9.9
10.4 Calculate analyte concentrations according to the fol-lowing equations:
RF 5 AA 3 MI
and
% Analyte 5AA 3 MI 3 100
AI 3 RF 3 MC (2)
where:
RF = response factor,
AA = area of analyte,
MI = mass of internal standard,
AI = area of internal standard,
MA = mass of analyte, and
MC = mass of coating
10.5 Repeat the procedure given in 10.3 using paint and internal standard amounts such that the relative peak areas of the analyte and its internal standard chromatographic peak areas are approximately the same size A duplicate injection of the same sample should give relative peak areas that agree within 1 % of each other
10.6 Samples may also be analyzed for acetone content using Test Method D6133
11 Precision and Bias
11.1 Precision—A round robin was conducted involving
five laboratories All of the laboratories used the SPME
TABLE 3 Approximate Retention Times and Masses of Analytes
and Internal Standards
Analyte/Internal Standard m/e Retention Time, min
Trang 4sampling technique Three of the laboratories used flame
ionization (FID) detection to measure analyte amounts and two
of the laboratories used mass spectral (MS) detection to
measure analyte amounts
11.2 Six commercial solvent-borne coatings were analyzed
Four of the coatings contained acetone and two of the same
four coatings contained both acetone and
parachlorobenzotri-fluoride Coatings containing methyl acetate were not yet
available in the marketplace and were therefore prepared by
adding known amounts of methyl acetate to different cellulose
nitrate lacquers
11.3 Precision data was calculated separately for the three
laboratories using FID detection and the two laboratories using
MS detection and also for the combination of FID and MS
detection Average values, repeatability standard deviations
(Sr), and reproducibility standard deviations (SR) are given for
each coating and exempt solvent inTable 4 andTable 5
11.4 The results were analyzed for precision using Practice
E180
11.5 Precision (Within-Laboratory, Between-Days
Variability, Formerly Called Repeatability)—The standard
de-viation of results (each the average of duplicates), obtained by
the same analyst on different days, have been estimated to be
0.42 % absolute at 39 df for acetone, 0.35 % absolute at 19 df
for parachlorobenzotrifluoride, and 0.16 % absolute at 19 df for
methyl acetate The 95 % confidence limit for the difference
between two such averages is 1.18 % absolute for acetone, 0.97 % absolute for parachlorobenzotrifluoride, and 0.46 % absolute for methyl acetate
11.6 Reproducibility (Multilaboratory)—The standard
de-viation of results (each of the average of duplicates), has been estimated to be 0.69 % absolute at 39 df for acetone, 0.53 % absolute at 19 df for parachlorobenzotrifluoride, and 0.25 % absolute at 19 df for methyl acetate The 95 % confidence limit for the difference between two such averages is 1.94 % absolute for acetone, 1.47 % absolute for parachlorobenzotrifluoride, and 0.70 % absolute for methyl acetate
11.7 Bias—Bias cannot be determined for this method
because there are no accepted standards for acetone, methyl acetate and parachlorobenzoptrifluoride in paints and coatings
12 Keywords
12.1 acetone; acetone content by GC; gas chromatography (GC); head space sampling; methyl acetate; methyl acetate content by GC; parachlorobenzotrifluoride (PCBTF); PCBTF content by gas chromatography; solid phase microextraction (SPME); VOC
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TABLE 4 Precision Data for Acetone
TABLE 5 Precision Data for Parachlorobenzotrifluoride and
Methyl Acetate
trifluoride
Methyl AcetateA
ACellulose nitrate lacquers obtained from different manufacturers were diluted under carefully controlled laboratory condition to give samples E and F The calculated values for methyl acetate in these two samples were: Sample E, 21.2 %; Sample F, 12.0 %.